Type III secretion system substrate exporter (IPR006135)

Short name: T3SS_substrate_exporter

Overlapping homologous superfamilies

Family relationships


Salmonella, and related proteobacteria, secrete large amounts of proteins into the culture media. The major secreted proteins are either flagellar proteins or virulence factors [PMID: 10564516], secreted through the flagellar or virulence export structures respectively. Both secretion systems penetrate the inner and outer membranes and their components bear substantial sequence similarity. Both the flagellar and needle like pilus look fairly similar to each other [PMID: 9554854].

The type III secretion system is of great interest, as it is used to transport virulence factors from the pathogen directly into the host cell [PMID: 10334981] and is only triggered when the bacterium comes into close contact with the host.

It is believed that the family of type III flagellar and pilus inner membrane proteins are used as structural moieties in a complex with several other subunits [PMID: 9618447]. One such set of inner membrane proteins, labeled "S" here for nomenclature purposes, includes the Salmonella and Shigella SpaS, the Yersinia YscU, Rhizobium Y4YO, and the Erwinia HrcU genes, Salmonella FlhB and Escherichia coli EscU [PMID: 9618447, PMID: 16246842, PMID: 8045883, PMID: 8169210].

Many of the proteins, in this entry, undergo autocatalytic cleavage promoted by cyclization of a conserved asparagine. These proteins belong to the MEROPS peptidase family N6.

GO terms

Biological Process

GO:0009306 protein secretion

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0016020 membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.